Nothing like a new release to remind me about the pain of migrating
custom patches to each release. If you would like to incorporate this
in a future release, please do.

I wanted specify which header sender field to verify, I've expanded the
verify=header_sender command. I also fixed some of the header syntax
checking to recognize some additional valid, and sometimes used, address
list formats.

* returns true if any sender header address is verifiable
all returns true if all header sender addresses are verifiable
from returns true if verifiable address in From: header line
reply_to returns true if verifiable address in Reply-To: header line
sender returns true if verifiable address in Sender: header line